TNS or TNC-S

[a1spark]

Does the lable not say "PME Conditions Apply" rather then "this property has a PME Earthing presentation" advising anyone that the source of the TN-C-S Earth (if used) is via a PME PEN?

Got to go to work now Ian, but I can say no more than what I have already stated ,and I am happy to go by the BRB. Thanks.

 

[ianmacd]

and I am happy to go by the BRB. Thanks.

Or happy to go with your interpritation of what it says even if thats not correct.

 

[a1spark]

I do hope the job i am going to turns out to be TNS or TT though after all this discussion Hee! Hee!

 

[Freetrader]

Thank you all , its good not feel alone out there,

Cheers

:Y

 

[initforthemoney]

TNS via concentric cable will usually have the CPC broken out before the supply cable enters the cutout and taken to a MEB.

If its TNCS (PME) then they will either remove the knock outs from the cut outs OR sometimes, install a MEB.

However, yes, the picture is PME.

 

[a1spark]

TNS via concentric cable will usually have the CPC broken out before the supply cable enters the cutout and taken to a MEB.If its TNCS (PME) then they will either remove the knock outs from the cut outs OR sometimes, install a MEB.

However, yes, the picture is PME.

AND a TNCS SYSTEM

 

[initforthemoney]

AND a TNCS SYSTEM

If you say so.

 

[a1spark]

Not me .but BS 7671 2008 Does

 

[ianmacd]

Aggrrr.

PME is not a correct term for an Earthing Arrangement for an Installation. Have a look over 542.1 and you will notice the lack of PME there.

 

[steptoe]

TNS via concentric cable will usually have the CPC broken out before the supply cable enters the cutout and taken to a MEB.If its TNCS (PME) then they will either remove the knock outs from the cut outs OR sometimes, install a MEB.

However, yes, the picture is PME.

NO its not,

unless it is labelled as such then you are only guessing,

 

[Sidewinder]

Steps,

Sorry Bud, back to perfect world again!

The problem being the split between DNO & metering operator.

Cut outs are often not labelled!

Not sying this is right but it does happen.

May well be in contravention of ESQCR!

All,

PME is a means of connecting the CNE conductor in the DNO supply system to earth at multiple points - Protective Multiple Earthing.

I'm not defending the design criteria!

Look up the definitions in ESQCR & the associated guidance and cross reference these to BS7671.

BTW, BS7671:2008 triggered an update to the ESQCR when issued so they are interlinked.

HTH

 

[steptoe]

Steps,Sorry Bud, back to perfect world again!

The problem being the split between DNO & metering operator.

Cut outs are often not labelled!

Not sying this is right but it does happen.

May well be in contravention of ESQCR!

All,

PME is a means of connecting the CNE conductor in the DNO supply system to earth at multiple points - Protective Multiple Earthing.

I'm not defending the design criteria!

Look up the definitions in ESQCR & the associated guidance and cross reference these to BS7671.

BTW, BS7671:2008 triggered an update to the ESQCR when issued so they are interlinked.

HTH

Im not about to argue with something I am not conversant with

(not tonight anyway for a change! )

but, IMHO if it doesnt have the label then I assume its simply a TNCS and NOT a PME

I like to ERR on the side of caution.

I know what the regs and ESQCR say, but do we believe everything we are told.?

 

[green-hornet]

I think I may write a paper on earthing myths, earthing is not rocket science.

Unless the DNO label "correctly" never assume an earthing arrangement.

The only earthing I can personaly advocate is TT,its the only sure and logical way to verify total earthing for any installation, if installed correctly.

I hate having to rely on a provided earth, which we almost always have to do, because any faults are beyond our control and possible total failure of earth is possible.

I know many of you would disagree, but that is your right and I will not disagree with your preference, like always its down to personal beliefs.

However I will say this, I have never come across any correctly installed TT installation with a failed earth, but I have with TN systems.

 

[steptoe]

we should probably do a poll on what have you got at home...

then do another one on

what have you got proof of you have at home....

wonder if anyone will admit to the difference,

ie be prepared to provide photo evidence of the TNCS actually being labelled as PME

come on guys, for all of you that have TNCS, send in your pix of PME labels,

 

[Sidewinder]

Steps,

I doubt you'll find many!!!

Not defending or supporting the system, but in the real world it seems all to pot!

IIRC & I don't think I'm allowed to put up the text of ESQCR, all TN-C-S distributions on the DNO side MUST be PME.

It is available on the internet, along with its guidance notes.

All,

Where do you all percieve the risk/hazard. I see it in the TN-C-S aspect and the PME as risk/hazard minimisation.

Comments...

Who can explain why there is such a "risk/hazard" in correct emotionless terminology.

Thnk about Steps N/E voltages...

Give me a few weeks and I'll revisit the topics I have fallen short on if I can.

Was going to say "debate" but debate is not what I am loking for, I'm looking for reasoned emotionless engineering reasoning on the topic.

Well folks...............

BTW, sorry a bit busy so not on much at the mo will try to look in as much as I can thought.

BIG problems, don't ask!

ATB

 

[initforthemoney]

It doesnt really matter if its TNS or TNCS.

As long as the Ze is within 0.35.

 

[Sidewinder]

Ahh, but it does as it depends on how the earth is "delivered".

That is what Steps is conerned with, and what I am trying to prompt you all with!

 

[Andy™]

It doesnt really matter if its TNS or TNCS.As long as the Ze is within 0.35.

Ze can be 0.8 for TNS...

 

[initforthemoney]

[quote name='Andy

 

[a1spark]

It doesnt really matter if its TNS or TNCS.As long as the Ze is within 0.35.

Hi Infor , It would matter if it Was a PIR that was being carried out, or planned additions to the installation though wouldnt it ?....Different criteria on sizing of Main Bonding Springs to mind.....Ze lower limits is not the only consideration between the two systems.